1. Field of the Invention
The present invention pertains to flexible foam compositions and in particular to flexible polyurethane flame-retarded foam compositions and methods for the preparation thereof. More particularly, the present invention relates to the preparation of flexible polyurethane flame-retarded foam compositions which contain an effective amount of a flame retardant compound and a graft polymer dispersion having a vinyl particle size greater than 0.5 micron.
2. Description of the Prior Art
The preparation of flexible polyurethane flame-retardant foam compositions are generally well known as evidenced by the following prior art. U.S. Pat. No. 4,022,718 teaches the preparation of high resilience cold-cured polyurethane foams incorporating 2,3-dibromo-1,4-butanediol as a chain extender and flame-retardant component. U.S. Pat. No. 4,147,847 teaches a method of preparing flexible, flame-retarded, polyurethane foams by employing specific foam stabilizers which reduce the required amount of normal flame-retardant additives. U.S. Pat. No. 4,162,353 teaches the preparation of flexible polyurethane foams incorporating therein a halo-substituted alkyl phosphate such as, for example, tris(2-chlorethyl)-phosphate and an unsubstituted trialkylphosphate such as, for example triethylphosphate.
U.S. Pat. No. 3,875,258 teaches the preparation of graft polymer dispersions in polyols employing monomers which have incorporated phosphorus and halogen in order to prepare urethane compositions having flame-retarding properties. The use of graft polymer polyol dispersions in flexible foams often necessitates the use of larger amounts of flame retardants to meet specific flammability tests, such as the California Bulletin No. 117 flame test, than is normally required for foams based on conventional polyether polyols. These higher levels of flame retardant result in higher foam costs and can result in foam processing difficulties. The present invention is directed to solving the problem involved in preparing flame-retarded graft polymer polyol containing polyurethane foams.